Just three Lamborghini 350/400GT chassis received special coachwork and one has been missing since the 1960s: until now.

The assignment is an appealing one: fly to Bologna, drive to Modena and check out the mystery Lamborghini that Bonhams’ MD Simon Kidston has unearthed, a 400GT bodied by Neri & Bonacini that hasn’t been seen for 35 years and that many believed lost. But, hold on, wasn’t the car found in Spain? And isn’t it to be sold in London, at Olympia on December 5? So what is it doing in Italy?

The answer is simple: a Miura owner himself, Kidston knows that waking a four-cam V12 from 35 years of slumber is a job for experts – and they don’t come better than Orazio Salvioli at Top Motors of Nonantola, just down the road from the Lamborghini factory where Salvioli worked from 1967 to 1997. It’s also an unmissable opportunity to reunite the car with its past and attempt to tease out the fact from the fiction among the stories that are circulating about this mystery Lamborghini.

Before we go, we check out what the press said when the car was new. Reports on the car appeared in Italian, US and French publications in 1966 and 1967. First, in August 1966, was Italian magazine AutoSprint, which showed side and interior views of ‘Una nuova Lamborghini’ and attributed it to carrozzeria ‘Autocorse, affiliated to Neri and Bonaccini [sic]’.

Then, in November, a far more detailed account occupied three pages of Road & Track magazine in the USA. Contributor Pete Coltrin was a permanent resident in Modena and he had followed the construction of the Monza 400; he related that the chassis had been purchased from Lamborghini by Neri & Bonacini ‘for their own design exercise, and it is reasonable to assume that this particular car has already been sold’. However, he also states ‘Neri & Bonacini build the chassis frames for the production Lamborghini’ which, by then, was incorrect as they had only built the first 20-30 chassis before handing over production to ex-employee Marquesi.

Finally, in 1967 French publication L’Automobile reported the launch of the Miura at Jarama circuit in Spain, where a surprise awaited: the event was also attended by none other than ‘our’ Monza, renamed ‘Jarama’ in honour of the Spanish circuit.

Landing in Bologna, we get in the mood by driving through Sant’Agata, where we find the Lamborghini factory at the side of the road, an impressive range of modern buildings fronted by a two-storey showroom where gems from the company’s past glow under spotlights as the evening closes in outside. Behind the service department lurk a well-used prototype bodyshell and a Lamborghini racing boat. Round the back we spot rows of new Gallardos and Murcielagos dressed up for dispatch to lucky buyers around the world; later we’ll see a couple at Bologna airport, being prepared for air-freight to owners with neither the time nor the inclination to wait for a ship to bring them.

Into Modena for a meeting with Dottore Adolfo Orsi at the Fangio exhibition he’s helped to organize for Modena City Council. Orsi’s grandfather and father owned Maserati during its halcyon years from 1937 to 1967. He grew up in the company of many great men, including Fangio, and spent much of his childhood in the factory, even enjoying blasts in a go-kart that was built there for children of the family: ‘It had a Bultaco engine and Vespa wheels,’ he recalls. ‘It was very noisy and exciting and felt really fast!’ By chance its current owner, the president of the local motor club, is sitting at the next table to us at dinner.

Orsi soon reveals that there’s a Maserati connection with our mystery Lamborghini, too: ‘Both Neri and Bonacini worked as mechanics for Maserati. Giorgio Neri was a Maserati racing mechanic when Fangio was racing. He opened his own race mechanic shop when Maserati stopped racing in 1957 and worked for privateers like Jo Bonnier. The first Lamborghini engine was built by Bizzarrini in the Neri & Bonacini workshop, as well as the first few chassis. They had a shop behind the Monza autodrome. You’ll meet Mr Neri tomorrow: he’s been out of cars for 30 years but he’s keen to see the Monza again.’

Simon Kidston arrives, hot-foot from business in Rome but eager to tell the story of how he found the Monza – and it transpires that he’s known of it for a long time.

‘I was working for Brooks in the 1990s,’ he recalls, ‘when we received photographs from Spain of a Porsche 906 that had been stored for decades. In the pictures I could just make out the shape of some other car behind, so I phoned up and asked what it was. I was told, “It’s some kind of Lamborghini, I’m not sure what.” I flew over and was entertained by the very reserved family owners. They took me to a busy street of shops, where they opened the metal door of one shop that had been bricked up in the 1960s. There, covered in dust, was a number of motorcycles, a speedboat, the Porsche and, right at the back, the Monza.

‘The man who showed me the car – the family don’t want their name to be revealed – explained that the car had been bought new by his uncle, straight off the Lamborghini stand at the 1967 Barcelona Motor Show. In the Franco era it was almost impossible for ordinary Spaniards to import foreign cars, but he had the right contacts.’

‘I think that if a dealer displayed a car at a motor show, he could register it afterwards,’ cuts in Adolfo. ‘Spain was the only market in which you could register a prototype as a new car at the time, which is why most of the special cars, like the Maserati Boomerang, went there.’

‘Apparently he really wanted the Miura that was displayed alongside it,’ continues Simon. ‘But when he was told there was a four-month waiting list, he decided to have the Monza instead. He was the classic old-money playboy – he never worked, never married, had lots of girlfriends and spent his life hunting, shooting, fishing, motorbike racing and car racing. His first racing car was a tuned Mini-Cooper but, when he decided that was too slow, he bought a new Porsche 906, then two years later a 908 and then an Alfa Tipo 33. Incidentally, thosetwo have never turned up: it’s possible they were left with someone and forgotten.

‘He had nudge bars fitted front and rear and changed the Monza badge for Jarama in honour of the Spanish racetrack – years before Lamborghini used the name – but he only drove the car for 7000km. He died in the early 1990s but the cars had been bricked up in the shop since 1970.’

Next morning we seek out Top Motors – a task that proves to be easier said than done, as this large and immaculate all-white workshop is hidden behind the most unassuming façade of industrial units, making it all too easy to miss. We’re warmly greeted by Orazio and Luca Salvioli, whose expertise with Italian V12s is such that the workshop is packed with Lamborghini, Maserati and Ferrari cars and parts from the last 50 years. Orazio unveils the Monza and explains that the engine will run, but the car needs work on clutch, brakes and electrics.

Long, low and lithe, this unique Lamborghini certainly looks different – yet there are familiar echoes in its lines. The flowing wing line is astonishingly similar to a Miura’s and the car is just as low, despite being front-engined. Period press photos haven’t done it justice: its styling is unusual, with a very low windscreen and the roofline sloping up behind it to the ‘basket handle’, a mock roll hoop over the back of the roof whose only real function is to conceal extractor vents for cockpit air. The cockpit behind the hoop is possibly its least attractive aspect, with large rear quarter panels that might have looked better turned into a wraparound rear screen, but it’s nicely finished off with a Kamm-type tail. It would be interesting to see the car with the roll hoop painted a contrasting colour: it might just work.

The nose bears the same hallmarks as the special Nembo (Neri & Bonacini) Ferrari 250GT spiders and coupé built in 1964-67; also the (apparently unrelated) Intermeccanica Italia of 1967. We’re just debating the styling when in walks Dutch Lamborghini fan Marcel de Lange, having driven all the way from Holland in a Smart just to see this lost Lamborghini. His laptop contains thousands of images of 350 and 400GTs, plus chassis records of every car. So how does chassis 1030 fit in?

‘Well, they’re not always in sequence,’ he explains, ‘but it’s certainly a late number, suggesting it’s one of the last 2+2 chassis.’ It’s a shame we can’t check the engine number, which is hidden under pipework between the heads.

Giorgio Neri arrives, delighted to see his old protégé again. In a mix of pidgin Italian and English, we grill him about the car.

‘It was ordered by a client – I think he was American – who wanted to race at Le Mans,’ he recalls. ‘That must have been in 1963 or 1964. However, he found out that he couldn’t get homologation so he left the car with Lamborghini. I’m not sure what happened to it then. This was the first car we built for Lamborghini – we’d made quite a few for Bizzarrini, but this was always intended to be a one-off.

‘The styling was a joint effort between myself and Luciano Bonacini. We built up the shape with a birdcage of stiff wires, then laid the aluminium over the wires. It was all done full-size, there were no drawings or plans. We’d make the shape, stand back and check the looks and proportions, then make changes – the nose a bit longer, the roof a bit lower, that sort of thing. Finally we were happy with the shape and the car was built.

‘We had a lot of problems with the windscreen, which is unique. We had to make a wooden buck and the glass had to be pulled around it; it took four or five attempts to get it right.’

Mr Neri heads home and we take a closer look inside the Monza. The seats are set very low, giving just-adequate headroom and a comfortable driving position. The instruments are quite nicely laid out and are in fact lifted wholesale from the Lamborghini 350/400 range. The row of toggle switches on the center console, though, is labelled with Dymo tape – in English. Why on earth does an Italian coachbuilt car, that spent its working life in Spain, have English labelling? Could this support the story that the car was originally built for an American?

For a one-off, the car seems well sorted; the doors have proper winding windows and there are interior lights in each footwell. It looks as if it may have been used for a rally, as a map light is fitted for the passenger along with a tray on top of the dashboard for pencils: it would be a fearsome rally machine with its fourcam V12 and lightweight body, but the oil cooler mounted in the airstream below the radiator looks terribly vulnerable.

Marcel points out that the steering wheel is the type fitted to early 350GTs: people’s memories can be unreliable on years, but Giorgio Neri’s assertion that the car was built in 1964 on a 350GT chassis may be correct after all... On the passenger side is a Lamborghini badge and alongside it, in unevenly applied transfers, 400GT. Just what is under this car? Even if it has a 400 engine, that proves little as it could have been added when the car was two years old, to make it more appealing for sale.

Help may be at hand, because the latest arrival is Valentino Balboni – test driver at Lamborghini since 1968:

‘I remember this car,’ he enthuses. ‘It came back to the factory for a checkover a week before I joined and people were still talking about it. They said it had been Neri & Bonacini’s proposal for a production body to Ferruccio Lamborghini, competing with Touring and Zagato. I’m sure it’s on a 350 chassis, probably one of the first. The dipstick is between the carburettors, which is a 350 feature – otherwise the engine and chassis look identical to a 400’s. Don’t take any notice of the chassis number, that could have come off a crashed car or simply beenallocated when they finally decided to send it to Barcelona.’

Before we leave, one more task remains. The Salviolis spring into action, priming the carburetors and pumping the throttle. The veteran V12 fires up, splutters, then gradually clears, settling to a smooth, quiet tickover. Luca Salvioli then adds to the mystery by stating that he’s convinced the car is on a 400 chassis and confirms that it’s fitted with the Lamborghini transmission, introduced late in the 350’s production run.

This Lamborghini is itching to share its secrets with a new owner – and we hope one day we may even get to drive it.

Farmer turned tractor-builder and industrialist Ferruccio Lamborghini had long harboured a liking for fast cars when, in 1962, he set up a new factory and a young, talented team to build world-beating cars.

Interestingly, chassis, engine and body for the first Lamborghini were all built by Neri & Bonacini, according to Giorgio Neri, though the bodywork is normally attributed to Sargiotto of Turin.

Technically, the Lamborghini 350GTV was nearer perfect than was credible for an all new company – but styling was its downfall. Lamborghini commissioned Franco Scaglione to style its body but heavily influenced the shape himself; the result received a lukewarm reception at Turin in 1963. Lamborghini turned to Touring to productionize the styling, resulting in a better but still compromised style.

Launched in 1964, the 350GT was a phenomenal performance car, turning out a 152mph top speed and 6.8sec 0-60mph with impressive refinement; a year later the engine grew to 4-litres and 320bhp to boost performance still further. Some 131 two-seaters were built, 23 with the 4-litre engine but 20 of those with steel bodywork, which added significantly to the weight of a car. Three specials were built: two Touring convertibles and one Zagato fastback.

All-steel and 2.5in taller with all-new panelwork, the 400GT 2+2 was almost unchanged in styling but, inevitably, was heavier. It also boasted a new Lamborghini-made transmission. In all, 224 of the 400GT 2+2 were sold, all but two with standard bodywork. Touring turned out the remarkable sporting estate Flying Star – and, say the books – the other was the Neri & Bonacini Monza. But was it? Our sources conflict and the mystery Monza has the last laugh: for now.